Track interlock and safety stop mechanism



March 17, 1942.` F. c. HARRIS E'r A1.

TRACK INTER-LOCK AND SAFETY STOP MECHANISM Filed Aug. 3, 1940 5 Sheets-Sheet 1 INVENTORS FRANK C' HARRIS RALPH T- Moo/2E l i j ATro/e/ve'vs March 17, 1942. F. c. HARRIS l-:TAL 2,276,272

TRACK INTERLGCK AND SAFETY STOP MECHANISM Filed Aug. 5, 1940 5 sheets-sheet 2 4 INVENTOR5 FRA/vk C- HARe/s A T7012 NEYS RALPH 'r' Moo/e5 l F. c. HARRIS ETAL 2,276,272y

TRACK INTERLOCK AND SAFETY STOP MECHANISM March 17, 1942.

Filed Aug. 3, 1940 5 Sheets-Sheet 3 lzvvzshrroR.` FRANK c- HAE/els RALPH 7" MORE A fram/Er:

March 17, 1942. F, C, HARRls ETAL I 2,276,272

TRACK, INTERLOCK AND SAFETY STOP MECHANISM 5 Sheets-Sheet 4 Q Nm y Filed Aug. s, 1940 INVENTOR5 FRA N/ c-.HARe/s E N e R a o o r MMT .A T H. PM

March 17, 1942. F, C, HARRlS 'E1-AL 2,276,272

TACK INTERLOCK AND SAFETY STO? MECHANISM Filed Aug. s, 1940 5 sheets-sheet s INVENTOR 72 /l//l/l 84 C." as ed' so 90' By RAL/TH. 7'- MOORE ATTaR/vys Patented Mar. 17, 1942 TRACK ENTERLOCK AND SAFETY STGP MECHANSM Frank C. Harris and Ralph T. Moore, Lakewood,

hio, assignors to The American Monotail Company, Cleveland, Ohio, a corporation of Chio Application August 3, 1940, Serial No. 350,278

20 Claims. (Cl. ltd-9S) This invention relates to track interlocking devices and more particularly to an improved safety interlocking mechanism for coupling an end of a movable track with an aligned end cf a stationary track.

In material handling equipment overhead tracks are commonly employed to support movable trolleys which carry a load suspended therefrom. Frequently, in factory installations, cranes are provided with a section of track extending transversely of the direction of movement of the crane and, as the crane moves along its path of travel, the crane track comes into alignment with one or more stationary tracks which lead to other parts of the shop. Various devices have been proposed for locking a movable or crane track to a stationary track when the two are in aligned position. Furthermore, it has been proposed to use safety stops which extend across the ends of both the movable and stationary tracks in a position to prevent a trolley from running olf of the tracks when the ends are out of alignment, but which stop may be moved out of track blocking position when the movable and i stationary tracks are in alignment so that free travel of the trolley from movable to stationary track, and vice versa, will not be interfered with. With previous apparatus of this general type a serious situation has existed when the trolley happened to be stopped closely adjacent to the end of either the movable or stationary track,

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when these ends were in alignment and the safety stop retracted, and a portion of the trolley interfered with the safety stop in such a manner that it prevented the stop from moving into track blocking position. When this situation arose, with the prior mechanisms, the crane operator could still release the interlocking pin or other means which held the two tracks in alignment and could then move the crane so that the movable track was out of alignment with the stationary track. Accidents have occurred under these circumstances because the trolley could drop oif of the end of the track inasmuch as the safety stop was held in its retracted or nonstopping position by a portion of the trolley. Personal injury and damage to equipment has resulted from such accidents, and it is among the objects of our present invention to provide a track interlock and safety stop whereby the interlock cannot be released until the safety stops are actually in track blocking position.

Other objects of our invention include: the provision of a track interlock of the type described whereby movement of the interlock pin and withdrawing of the safety stops is positively prevented until the connecting rails or tracks are substantially exactly in alignment; the provision of an automatic track interlock' and safety stop which may be preset as the movable track approaches the connecting track so that when the two tracks come into alignment the interlock will automatically function and the safety stops on both tracks be withdrawn or retracted; the provision of a track interlock and safety stop whereby movement of the track interlocking mechanism actuates the safety stops on both tracks and whereby the track interlock cannot be withdrawn to disconnect the two tracks unless the safety stop on each track is at the same time moved into track blocking position; the provision of a track interlock and safety stop mechanism in which a sliding pin or bolt is employed as an interlock and connections are maintained between the bolt and the track blocking stops whereby the bolt cannot be withdrawn from interlocking position when a trolley is in position to block either of the safety stops, or a stop is stuck or jammed; the provision of a 'completely automatic and entirely fool-proof track interlock and safety stop which positively prevents movement of one track away from the other unless the track stops are in track blocking position; and the provision of apparatus of thetype described which is simple in form,k rugged, and economical to manufacture.

The above and other objects of our invention will appear from the following description of several embodiments thereof, reference being had to the accompanying drawings, in which:

Figure 1 is a plan view of one embodiment of our improved track interlock and safety stop mechanism, the parts being in the positions they assume immediately prior to interlocking movement of the bolt, the bolt latch being released and the tracks being aligned.

Figure 2 is a vertical cross-sectional taken on line 2 2 of Figure 1.

Figure 3 is a fragmentary side elevational View takeny substantially on line 3 3 of Figure 1.

Figure 4 is a horizontal cross-sectional view taken on line d-l of Figure 2 showing the track safety stop or butterfly in track blocking position.

Figure 5 is a transverse vertical cross-sectional view -vew taken on line 5-5 of Figure 2.

Figure 6 is a plan view, generallysimilar to Figure 1, but showing the parts in the positions they assume immediately after the interlocking bolt Vor plunger has moved into locking position.

Figure 7 is a vertical cross-sectional view taken on line I-'I of Figure 6.

Figure 8 is a horizontal cross-sectional view taken on line 8-8 of Figure 7 showing the track stop or butterfly in non-blocking position.

Figure 9 is a vertical cross-sectional view taken on line 9-9 of Figure 7.

Figure 10 is a side elevation of a modified form of interlocking apparatus for accomplishing the objects of `our invention, the tracks being illus-` trated in disaligned position.

Figure 11 is an illustrative plan View, ona reduced scale, showing the positions of the stationary and movable tracks of the apparatus illustrated in Figure 10.

Figure 12 is a vertical cross-sectional view taken on line I2-I 2 of Figure 10.

Figure 13 is a vertical cross-sectional view taken on line I3-I3 of Figure 10.

Figure 14 is a view generally similar to Figure 10 but illustrating the xed and movable tracks in aligned position with the locking bolt engaged and the tracks stops lifted out of track blocking position.

Figure 15 is a diagrammatic plan view general- 1y similar to Figure 11 but illustrating the tracks in aligned position.

Figure 16 is a fragmentary end elevation of the movable track structure taken substantially on line I6-I6 of Figure 14.

Figure 17 is a fragmentary horizontal crosssectional view taken on line I'I-II of Figures 14 and 18.

Figure 18 is a side elevational view of the locking bolt sleeve on the stationary track and its associated parts.

Figure 19 is an end elevation taken on line I9I9 of Figure 18.

Figure 20 is a view similar to Figure 17 but showing the locking bolt and pawl in disengaged position.

Figure 21 is a diagrammatic plan view of the pre-setting and operating mechanism for the interlock and safety stop apparatus shown in Figures 1 to 9 inclusive, the bolt operating spring being released.

Figure 22 is a side elevation of the apparatus shown in Figure 21.

Figure 23 is la View similar to Figure 21 but showing the bolt operating spring in pre-set or compressed position.

Referring to Figures 1 and 2, the movable or crane track is indicated at I and the stationary or connecting track at 2. .It will be understood that these tracks may be of any suitable form, a standard monorail track being illustrated, and that the crane track will be supported on suitable wheeled carriages for movement into and out of alignment with the connecting track 2.

As shown in Figures 1 and 2, the tracks I and 2 have just come into alignment and the views are taken just as the interlock latch member 3 has released theoperating interlock bolt 4 but before the bolt 4 has moved. Secured to the ends of the tracks I and 2 are the interlock mechan ism housings and 6. The housing 5 is carrieddisposed in a transverse slot I5 in the co-acting plunger 8. A portion of the inner side of bolt 4 is cut away at I6 and a portion of the plunger 8 similarly cut away at I I to permit limited sliding movement of the bolt 4 and plunger 8 in the slot 'I of the housing 5.

In order to exert a force tending to advance the plunger 8 and retract the operating bolt 4 we provide a compression spring I8 which engages the housing 5 at one end and has its opposite end disposed in a hole in the plunger 8. This spring tends to move the plunger 8 to the right into the position shown in Figure l and this movement is transmitted through the pins I3 and I 2, and the disc 9, to tend to move the operating bolt 4 to the left into the retracted position as shown in Figures 1 and 2. The main function of this spring I8 is to prevent undesired movement of the parts into track locking position due to jarring or vibration.

'I'he locking end of the bolt 4 is tapered as seen in Figure 1 and is notched at I9, as seen in Figure 2. This notch I9 is engaged by the corner 3a of the latch 3 which comprises a generally U-shaped member having a latching portion indicated at 3 and arms 20 and 2l extending along the sides of the housing 5. Trunnions 22 and 23 are formed on the ends of the arms 20, 2| and are disposed in slots 24 and 25, respectively, in

`the top of the housing 5. A latch lifting dog 26,

of generally V shape, extends into overlapping relation with the stationary track 2 and is adapted to engage and be lifted by the inclined cam surfaces on the stationary housing 6.

In Figures 1, 2 and 3, the latch 3 is shown in elevated or interlocked position with the dog 26 riding on the high point of the cam surfaces 21 and with the bottom corner 3a of the latch lifted clear of the top edge of the notch I9 of the operating bolt 4. As will appear more fully later, this position of the parts under some circumstances will obtain only instantaneously when the lifting dog 26 reaches its high point and the corner 3a just clears the notch I9 as, immediately upon release of the bolt 4 of the latch 3, the spring 28, provided it has been pre-compressed by suitable means such as shown in Figures 21, 22 and 23, will move the bolt 4 to the right into track interlocking position. If, however, the spring 28 has not been pre-compressed, the spring I8, and the pre-setting mechanism to be described later, will maintain the plunger 8 and bolt 4 in the positions shown in Figures 1 and 2 and no interlocking of the tracks will take place, thus permitting the movable track to pass by the stationary track without interference.

The means for selectively applying compression to the spring 28 or leaving the spring 28 uncompressed, are shown in Figures 21, 22 and 23 and will be described later.

The housing 6 supports parts which are generally similar to those carried by the housing 5. A plunger 29 is generally similar in form to the plunger 8 but is disposed opposite to the operating bolt 4 when the tracks are in alignment, as shown in Figures 1 and 2. This plunger 29 is slotted at 39 to accommodate the pin 3l carried by the disc 32. Opposite pin 3| on the disc 32' is a second pin 33 which is disposed in a transverse slot 34 in the bolt 35. A compression spring 36 engages the housing 6 at one end and the plunger 29 at its opposite end and functions in the same manner as the spring I8 described above. The track safety stop for the xed track 2 takes the form of a rotatable plate or buttery 31 secured to the shaft 38 which is rotatably supported in the housing 6 and carries the disc 32 at its upper end. Movement of the plunger 29 and bolt 35 is restricted by slots 39 and 40 which are formed in the inner side faces ofthe plunger 29 and bolt 35, respectively, and which are adapted to engage the shaft 3S to limit movement of the bolt 35 and plunger 29.

A wheel of a work supporting trolley is indicated at 4I and it will be observed that when the stops II and 31 are in their crosswise positions, as shown in Figures 1 and 2, the trolley wheels cannot pass by the stops and thus the trolley cannot fall ofi of the end of the track. It will also be understood that when the tracks I and 2 are out of alignment the parts will assume the positions shown in Figures 1 and 2 with the exception that the latch 3 will be dropped into engagement with the notch I9 of the operating bolt 4. This latching action occurs automatically due to the weight of the member 3 when the bolt 4 is retracted by pulling on the connecting rod 42 which extends to the operating means shown in Figure 21- Figures 6 and 7 illustrate the parts in track interlocking position with the safety stops I I and 31 in non-blocking position in which, as is clearly seen in Figure 8, they extend parallel to the tracks I and '2 and oifer no obstruction to free passage of the wheels 4I of the trolley 43. Assuming that the tracks I and 2 are out of alignment, the latch 4 in retracted position as shown in Figure l, and the plunger 8 in advanced position, the latch 3 engaging the notch IS in the bolt 4 and holding the bolt in retracted position, and the spring v28 compressed: when the tracks I and 2 approach aligned position the dog 23 rides up on the adjacent inclined cam surface 21 on the housing and, just as the tracks I and 2 are substantially in alignment, the latch 3 is lifted suiiiciently to release the bolt 4. Figure 2 illustrates the parts just as such release occurs. The bolt 4 may then be pushed forward by the compression spring 28 into the position shown in Figure 7. This forward movement of the bolt 4 causes its end to engage the end of the plunger 29 pushing it inwardly into the position shown in Figure 7.

As the plunger 29 is connected to the disc 32 through the pin 33 this movement of plunger 29 will turn the disc 32 causing the pin 3I to advance the bolt 35 into the position shown in Figure 6. As the bolt 35 advances the plunger 8 retracts. During the forward movement of the bolt 4 and the rearward movement of the plunger 29 the discs 9 and 32 ore each rotated in counter clockwise direction as seen in Figure 6. This rotation is substantially 90 in extent and turns the stop members II and 31 from their transverse or track blocking positions shown in Figures 2 and 4 into their non-blocking positions shown in Figures 7 and 8. 'I'he tracks I and 2 are now definitely locked in alignment and the stops II and 31 are withdrawn to permit free passage of the trolley past the track joint.

When the operator desires to move the crane or movable track I he pulls on the operating rod 42 moving the bolt 4 to the left (Figure '1). This movement turns the disc 9 through the connecting pin I3 and advances the plunger 8 into the position shown in Figure 1. This advancing movement of the plunger 8 pushes the bolt 35 into its retracted position as shown in Figure 1 and this movement of the bolt 35 is transmitted by the disc 32 and pins 3| and 33 to the plunger 29 causing it to resume its unlocked position, as

be turned into their track blocking positions and the trolleys will be prevented from running off of the open ends of the tracks.

An important advantage of our invention will appear if it is assumed that a trolley happens to stop with its wheels or other part of the carrier interfering with either the stop II or the stop 31. Under such circumstances the wheels will prevent turning movement of the engaged stop. Regardless of whether the stop II or the stop 31 is blocked by a trolley, withdrawal or unlocking of the bolts 4 and 35 will positively be prevented as these bolts cannot be withdrawn unless both stops II and 31 can turn. When the operator attempts to withdraw the bolt 4 and it will not' move sufficiently to disengaged the interlock between the two tracks, he immediately knows that there is an obstacle in the way of one of the stops I I or 31. He then moves the trolley back on the track away from the open end until it clears the engaged stop whereupon he can withdraw the bolt 4 and release the interlock between the two tracks. It will be seen that with this arrangement it is impossible to move the tracks out of alignment unless the two stops I I and 31 are in track blocking position and this safety feature has completely overcome the troubles experienced with previous devices in which it was possible to release the interlocking bolts without setting the stops in track blocking position.

In Figures 21, 22 and 23 we have rather diagrammatically illustrated an varrangement for pre-setting the spring 23 whichencompasses the operating rod 42 and is adapted to force the bolt 4 intovinterlocking position. In Figures 21 and 22 the bolt 4 is retracted and is held in retracted position by the latch 3. The rod 42 extends freely through vthe end 34 of a yoke member 95 and is provided with adjustable abutment nuts 36 disposed in the slot 91 of the yoke 95. A bell crank lever having a long arm 38 and a short arm 99 is pivotally supported at |30 on the track structure. either in position to release the spring 28 or compress spring 28 we provide a snap-over spring IilI which is attached at one end to the outer end of the bell crank arm 98 and at its opposite end to a fixed pin |02 mounted on the track structure or any other suitable location.

The spring IIlI is always maintained under tension and in the position shown in Figure 21, it tends to swing the bell crank arm 93 in clockwise direction. This in turn tends to retract the bolt 4 due to the engagement of the nuts 93 with the end of the slot 91 in the yoke 95. When in this position the spring 28 is completely released and if the latch 3 be lifted to unhook the bolt 4 there will be no tendency for the bolt 4 to move out into interlocking position. The bolt operating unit is set as shown in Figures 2l and 22 when it is desired to permit the crane to pass by one or morer connecting tracks withoutv interlocking.

Now, if the operator desires automatically to interlock the crane track with the next connecting track he swings the bell crank arm 98, through any suitable operating connection such as chains or ropes, from the position shown in Figure 21 into that shown in Figure 23. During this movement the latch 3 prevents movement of the bolt 4 and rod 42 but the yoke 95 is moved forward by the bell crank arm 99, compressing the spring 28 as shown in Figure 23. During this compression In order to maintain the bell crank of spring 28 the yoke 95 merely slips over the rod 42. When the tension spring passes over the center line between pivot point |00 and pin |02 it snaps over into the position shown in Figure 23 and, as the spring |0| is stronger than the spring 28, it will hold spring 28 compressed.

The above described position of the operating unit may be termed the pre-set position as, when the spring 28 is so pre-compressed, the bolt 4 will automatically snap into interlocking position with a connecting track as soon as the latch 3 is lifted by the cam 21 to release its engagement with the notch |9 of the bolt 4. As illustrated, the bell crank arm 98 is disposed above the top flange |03 of the track supporting structure and the bell crank arm 99 is disposed below the flange |03 so that the connecting pin |04, between the yoke 95 and bell crank arm 99, is disposed substantially in the plane of movement of the bolt 4.

With this pre-setting apparatus the operator can leave the spring 28 released until he aligns the movable track with the stationary track and can then swing the arm 98 over its center position to cause the spring 28 to be compressed and the bolt 4 advanced into interlocking position. As an alternative, the operator may pre-set the apparatus by moving the bell crank arm 98 into spring compressed position, as shown in Figure 23, before the moving track reaches alignment with the stationary track and, with the spring 28 so pre-set, the interlock will automatically engage and the safety stops be retracted as soon as the two tracks are aligned and the latch 3 lifted by the cam 21 to release the bolt 4 and permit it to snap into interlocking engagement with the mechanism on the other track.

Another embodiment of our improved apparatus is illustrated in Figures 10 `to 19. This form of our invention is particularly adapted for heavy crane structures.

The movable track 44 is carried by a crane or the like which is indicated at 45 in Figure 11 and which includes a suitable end carriage 46 mounted on wheels 41 which are supported on a track 48. A stationary track 49, as illustrated in Figures 10 and 11 is disposed out of alignment with the movable track 44, but is illustrated in aligned position in Figure 14.

The track interlocking bolt 50 is mounted for sliding movement in a sleeve secured to the end of the movable track 44. Movement of the bolt 50 in and out through the sleeve is effected by the connecting rod 52 which has a pivotal connection at 53 with the end of the bolt 50 and which is connected at its outer end to a crank 54. Oscillation of the crank 54 is effected by suitable connections, either power or manual but not shown, to an operating wheel 55 and results in inand-out movement of the bolt 50.

A bell crank 56 has a lug 51 at its upper end disposed in a longitudinally extending groove or slot 58 in the bolt 50. The lower end of the bell crank 56 engages a socket 59 in the lever arm 60 and it will be seen that movement of the bell crank 56 about its pivot point 6| will lift or lower the lever 60. A track stop bar 62 is supported for vertical movement into and out of track blocking position in a guide 63 and is pivotally and slidably connected to the outer end of the lever 60 at 64. An elbow 60 is formed in the lever 60 and is adapted to rest upon the bottom flange of the track 44 thus limiting the downward movement of the stop 62.

In the bolt retracted position seen in Figure the left hand end of the slot of the groove 58 engages the left hand side of the lug 51. When the wheel 55 is turned to move the connecting rod 52 and advance the bolt 50 into track interlocking position, the initial movement of the bolt 50 will merely take up the lost motion between the ends of the slot 58 and the lug 51. No lifting movement of the stop 62 will occur until the right hand surface of the slot 58 engages the right hand surface of the lug 51 (Figure 10), whereupon further movement of the bolt 50 in track interlocking direction will swing the bell crank 56 counter-clockwise and lift the stop 62 into a position to permit free passage of a trolley or carrier structure.

An automatic latch 65 consists of a transverse bolt locking member and supporting side arms 66 and 61 which are pivotally supported at 68 and 69 (see Figure 13) on the crane structure. Cam roller 10 projects from the front face of the latch 65 beyond the intersection line of the adjoining tracks 44 and 49. In Figures 10 and 13 the latch is shown in bolt locking position and it will be observed that the face of the transverse bar of the latch 65 covers the tapered end 50' of the bolt 50 and prevents outward movement of the bolt into interlocking position.

An inclined or V-shaped cam 1| is mounted on the top of the stationary track 49 and is disposed in the path of the cam roller 10. As the movable track 44 advances toward aligned position with a stationary track 49 the cam roller 10 will ride up upon the adjacent inclined cam surface 1| thus lifting the latch 65 until the lower edge thereof clears the point of the bolt 50. This clearance of the point of the bolt occurs only when the two tracks are substantially in alignment and the operator can then turn the wheel 55, which can be either power or manually operated, to advance the bolt 50 into locking position as shown in Figure 14.

Mounted on the stationary track 49 is a sleeve member 12 which guides and supports a plunger 13. Pivotally supported on the track structure 49 at 14 is a bell crank lever, the upper arm 15 of which has a lug 16 disposed in a slot 11 in the plunger 12. The lower arm 18 is connected to the track safety stop bar 19 and oscillation of the bell crank 14 will lift or' lower the stop 19. A suitable bracket guides the up and down movement of the stop 19.

Secured to and extending from the plunger 13 is a rod 8| having a sliding fit in a fixed supporting bracket 82. This rod 8| carries a spring 83 which abuts against the end of the plunger 13 and the bracket 82 exerting a force tending to move the plunger 13 to the right (Figure 14).

As is clearly seen in Figures 17, 18 and 19, the end 50' of the bolt 50 is tapered and is provided with a hole 84 extending a short distance into the tapered portion 50. 'I'he end of the plunger 13 is slotted at 85 to accommodate a swinging latch or pawl 86, pivotally supported on a pin 81 which extends across the slot 85. This pawl 06 has a hooked inner end 88 and a follower lug portion 89 (see Figure 19) disposed generally opposite the hooked portion 88. A locking cam 90 is formed on the inner surface .of a member 9| secured to the sleeve 12 and extending radially from the side thereof. This cam surface 90 has a deep portion 90 and a relatively shallow portion 90".

After the tracks 44 and 49 have been aligned and the latch or keeper 65 has been raised to clear the point of the bolt 50 the bolt may be moved into locking position, i. e., to the left from the position shown in Figure 10 into the position shown in Figure 14. During this movement the end of the bolt l) engages the end of the plunger 73 and pushes it inwardly against the spring 83. As the bolt 50 moves into the sleeve 12 the hook 88 on the pawl 85 is swung up into the hole 84 in the end of the bolt 5E! as the follower lug member 89 moves from the deep portion 9E of the cam surface Si) to the shallow portion 90". i/Vhen the parts are in the position shown in Figure 17, the bolt 59 is at the limit of its locking movement and the hooked end 88 of the pawl 85 is in the hole 84 in the bolt 5t. As the plunger i3 is moved inwardly the bell crank arm 'i6-'I8 is moved counter-clockwise, lifting the stationary track stop bar 19 into non-blocking position as shown in Figure 14.

Thus, as illustrated in Figure 14, the bolt 5i] is in track interlock position and both track stops 62 and i9 have been retracted to permit free passage of a trolley or carrier frame thereby. When the operator desires to release the track interlock he retracts the bolt 5S by turning the wheel 55. 5D is follOwed up by a forward movement of the plunger 'i3 under the iniiuence of the spring 83. While the pawl follower lug 86 is engaged in the hole 84 the bolt 5B cannot be pulled free from its connection to the plunger 13 and this connection is maintained until the follower 89 reaches the deep portion Sil' of the cam surface Sil. When this point is reached additional movement of the bolt 12 causes the edge of the hole 2li to engage the edge of the hooked end S8 and swing the pawl 3S so that follower lug S9 drops into the deep part 9B of the cam 9B. Now the bolt 5t is completely released from its connection to the plunger '13 and it may be entirely withdrawn from interlocking engagement with the stationary track sleeve l2. During this withdrawing movement of the bolt 5G the track stop 62 is moved downwardly into blocking position and similarly, as the plunger 'i3 advances, the track stop 'i9 is moved downwardly into blocking position.

If any obstacle is offered to downward movement of either the stop 62 or stop F9 the operator will be unable completely to withdraw the bolt 50 because the interengagement of the pawl hook 88 in the hole 84 prevents complete withdrawal of the bolt 5l?. Thus, if a trolley or carrier frame is disposed beneath either of the stops 52 or 'I9 these stops cannot be moved down into their blocking positions and, even though they may move part way, the pawl 86 will not be released unless the stops are down sufficiently far to properly protect the track ends. The degree of downward movement of the stops 62 and 79 which must be completed before the bolt 50 can be completely released is determined by the length of the shallow portion S9" of the cam surface $0.

In Figure 16 a form of carrier structure is illustrated having wheels 92 supported on the track M and a frame 93 carried by the wheels. If this frame S3, or any part thereof, is disposed in the path of the stops 62 or 'IS it will not permit sufficient movement of the bolt 56 and the plunger 'I3 to the right (from the position shown in Figure 1'7) to permit the follower 39 to drop into the deep portion dii' of the cam.

The spring 33 is employed largely to cause the plunger 73 to follow up the bolt 50 as it is withdrawn and thus reduce wear on the innercorner of the hooked end B8 of the pawl 85 which This retracting movement of the bolt would occur if the bolt 50 had to pull the pawl 86 and plunger 13 along with it during each rer'- tracting movement. f

From the above description of the embodiment of our invention shown in Figures 10 to 19, it will be seen that the operator is positively prevented from releasing the interlock bolt unless both track stops are in track blocking position.

Both forms of our invention, through the bolt blocking latch, prevent an operator from care-v lessly throwing the bolt out and withdrawing the safety stops at any time except when the rail or track which carries the latching device is l infregistry with another track. This completely eliminates the danger which arises with apparatus in which the locking bolt can be thrown when the tracks are not in alignment due to the bolt projecting and striking the lends of connecting tracks with resulting 'damage to equipment and possible injury to the operator, to say nothing of the possible danger rof running a trolley and loadoff the track when the stops are in non-blocking position.

' Our improved track yinterlock and safety mechanism prevents disengagement of the interlock if a trolley or carrier frame interferes with the movement of the safety stop into blocking position. It further prevents disengagementA of the interlock if the safety stops would stick or become jammed or if any part of the operating linkage or lever system should jam. Thus, we have provided a completely fool-proof interlock and safety stop' for apparatus of the type described and, although we have described the illustrated 'embodiments of our invention in considerable detail it will be understood by those skilled in the art that numerous variations and modifications may be made in the specific arrangement of parts and form of elements employed and we do not, therefore, wish to be limited to the vparticular form of our safety interlock herein shown and described, but claim as our invention all embodiments thereof coming within the scope-of the appended claims.

We claim:

1;'In.track blocking and interlockingapparatus, tracks adapted to be moved relatively into and out of end to end alignment, bolt 'interlocking means, means for moving said bolt across the ends of said tracks when aligned to interlock same, a safety stop adjacent each track end, means operable upon movement'of said bolt into interlocking position to move said stops out of track blocking position and to return said stops' to track blocking position upon withdrawal of said boltfrom interlocking position, and means operatively connecting said bolt and said stops for preventing complete withdrawal of said bolt frorninterlocking position except when each of said stops is free to move into effective track blocking position.

2. In track blocking and interlocking apparatus of the type described, track members disposed for relative movement into and out of end to end alignment, an interlocking bolt supported adjacent the end of one of said tracks, a safety stop adjacent the end of said one of said tracks, connections between said bolt and stop whereby movement of said bolt into interlocking position moves said stop into non-blocking position relative to said track rand movement of `said bolt out ofinterlocking position moves said stop into track blocking position, a plunger supported adjacent the end of the other of said tracks, a second safety-stop adjacent the end of said other of y said tracks, connections between said plunger and second stop whereby movement of said plunger away from said other track end moves said second stop into non-blocking position and movement of said plunger toward said other track end moves said second stop into track blocking position, and means carried by said bolt carrying track for maintaining said bolt in interlocking position when either ofsaid safety stops; are held in nonblocking position.

3. In track interlocking and safety stop mechanism, a pair of tracks adapted to be moved relatively into and out of end to end alignment, a movable interlocking bolt mounted adjacent the end of one of said tracks, a plunger mounted adjacent the end of the other of said tracks and disposed opposite said bolt and in the line of movement thereof when said track ends are aligned, safety stops carried by said tracks and adapted to be moved into and out of track blocking position, operating connections between said bolt and one of said stops, operating connections between said plunger and the other of said stops, a latch member positioned to retain said bolt in withdrawn position, and latch actuating means means for moving said bolt into and withdrawing said bolt from said receptacle when said track ends are aligned, and latch means pivotally carried by said bolt carrying rail for retaining said bolt in withdrawn position at all times except when said ends are aligned.

5. In track interlocking mechanism, a pair of tracks mounted for movement relatively into and out of end-to-end alignment, a bolt carried by one track, a receptacle for said bolt on the other track, means for moving said bolt into and out of said receptacle when said track ends are aligned, latch means pivotally carried by said bolt carrying rail for retaining said bolt in withdrawn position at all times except when the rail ends are aligned, a safety stop adjacent each track end, means operable upon movement of said bolt into said receptacle to move said stops out of track blocking position and to return said stops to track blocking position upon withdrawal of said bolt from said receptacle, and means operatively connecting said bolt and said stops for preventing complete withdrawal of said bolt from said receptacle except when each of said stops is free to move into effective track blocking position.

6. In track interlocking and safety stop mechanism, a pair of tracks adapted to be moved relatively into and out of end to end alignment, a movable interlock bolt mounted adjacent the end of one of said tracks, a plunger member mounted adjacent the end of the other of said tracks and disposed opposite said bolt and in the line of movement thereof when said track ends are aligned, safety stops carried by said tracks and adapted to be moved into and out of track blocking position, operating connections between said bolt and one of said stops, operating connections between said plunger and the other of said stops, and means operatively connected to said bolt and to said plunger respectively for preventing substantial separation of said bolt and plunger during movement thereof toward the track on which said bolt is carried until said safety stops are moved into track blocking position.

7. Track blocking and interlocking mechanism including tracks adapted to be moved relatively into and out of end to end alignment, housing members supported one on each of said tracks, one of said tracks being fixed and the other movable, a track interlocking bolt slidably supported in the movable track housing, a plunger disposed adjacent to said bolt and also slidably supported in said movable track housing, means for interconnecting said bolt and plunger whereby movement of said bolt in one direction will be accompanied by movement of the plunger in the opposite direction, a track safety stop operable by said bolt and plunger interconnecting means, said safety stop being disposed in track blocking position when said bolt is withdrawn or retracted into said housing and moving into non-blocking position when said bolt is advanced into interlocking position, a second plunger slidably carried by said housing on said stationary track and adapted to be disposed opposite said bolt when said tracks are substantially in alignment, a second bolt disposed in said stationary track housing adjacent said second plunger, said second bolt being disposed in alignment with said rst named plunger when said tracks are in alignment, means for interconnecting said second plunger and said second bolt whereby movement of said second plunger away from the stationary track end will advance said second bolt into interlocking position, a second safety stop operatively connected to said interlocking means for said second bolt and plunger, said second safety stop being disposed in track blocking position when said second bolt is retracted and moving into non-blocking position when said second bolt is advanced, and means for advancing and retracting one of said bolts to and from track interlocking position.

8. Track blocking and interlocking mechanism including tracks adapted to be moved relatively into and out of end to end alignment, housing members supported one on each of said tracks,

one of said tracks being fixed and the other movable, a track interlocking bolt slidably supported in the movable track housing, a plunger disposed adjacent to said bolt and also slidably supported in said movable track housing, means for interconnecting said bolt and plunger whereby movement of said bolt in one direction will be accompanied by movement of the plunger in the opposite direction, a track safety stop operable by said bolt and plungerV interconnecting means, said safety stop being disposed in trackblocking position when said bolt is withdrawn or retracted into said housing and moving into non-blocking position when said bolt is advanced into interlocking position, a second plunger slidably carried by said housing on said stationary track and adapted to bedisposed opposite said bolt when said tracks are substantially in alignment, a second bolt disposed in said stationary track housing adjacent said second plunger, said second bolt being disposed in alignment with said first named plunger when said tracks are in alignment, means for interconnecting said second plunger and said second bolt whereby movement of said second plunger away from the stationary track end will advance said second bolt into interlocking position, a second safety stop'operatively connected to said interlocking means for said second bolt and plunger, said second safety stop being disposed in track blocking position when said second J bolt is retracted and moving into non-blocking position when said second bolt is advanced, means for advancing and retracting one of said bolts to and from track interlocking position, and latch means carried by said movable track housing for retaining said movable track bolt in withdrawn position.

9. Track blocking and interlocking mechanism including tracks adapted to be moved relatively into and out of end to end alignment, housing members supported one on each of said tracks, one o said tracks being Xed and the other movable, a track interlocking bolt slidably supported in the movable track housing, a plunger disposed adjacent to said bolt and also slidably supported in said movable track housing, means for interconnecting said bolt and plunger whereby movement of said bolt in one direction will be accompanied by movement of the plunger in the opposite direction, a track safety stop operable by said bolt and plunger interconnecting means, said safety stop being disposed in track blocking position when said bolt is withdrawn or retracted into said housing and moving into non-blocking position when said bolt is advanced into interlocking position, a second plunger slidably carried by said housing on said stationary track and adapted to be disposed opposite said bolt when said tracks are substantially in alignment, a sec.- ond bolt disposed in said stationary track housing adjacent said second plunger, said second bolt being disposed in alignment with said rst named plunger when said tracks are in alignment, means for interconnecting said second plunger and said second bolt whereby movement of said second plunger away from the stationary track end will advance said second bolt into interlocking position, a second safety stop operatively'connected to said interlocking means for said second bolt and plunger, said second safety stop being disposed in track blocking position when said second blot is retracted and moving into nonblocking position when said second bolt is advanced, means for advancing and retracting one oi said bolts to and from track interlocking position, and latch means carried by said movable track housing for retaining said movable track bolt in withdrawn position, said latch having a portion projecting over the junction line of the track ends, and means on said stationary track end for engaging and moving said latch to release said movable track plunger when said track ends are substantially in alignment.

10. In track interlocking apparatus, a pair of tracks adapted to be moved relatively into and out of end to end alignment, an interlocking bolt supported adjacent the end of one of said tracks, means for receiving said bolt carried adjacent the end of the other of said tracks, an operating rod secured to said bolt, latch means for retaining said bolt in withdrawn position, a compression spring encompassing said operating rod and abutting against said bolt at one end, a yoke member through which said rod freely passes, said yoke member engaging the opposite end of said compression spring, a stop member on the end of said rod beyond said yoke, bell crank means having a iixed pivot and having one arm thereof connected to move said yoke toward and away from the end of the track, a tension spring having one end connected to the outer end of the'other arm of said bell crank lever and its other end secured to a fixed support, said tension spring being adapted to lie on one side of the center line between the iixed support for said tension spring and the xed pivot of said bell crank arm when in bolt retracted position and to lie on the other side of said center line when in pre-loaded or bolt operating position, saidtension spring being stronger than said compression spring.

11. In track interlocking apparatus, a pair of tracks adapted to be moved relatively into and out of end to end alignment, aninterlocking bolt supported adjacent the end of one of said tracks, means for receiving said bolt carried adjacent the end of the other of said tracks, an operating rod secured to said bolt, latch means for retaining said bolt in withdrawn position, a compression spring-encompassing said operating rod and abutting against said bolt at one end, a yoke, member through which said rod freely passes, said yoke member engaging the opposite end of said compressionspring, a stop member on the end of said rod beyond said yoke, bell crank means having a fixed pivot and having one arm thereof connected to move said yoke toward and away from the end of the track, a tension spring having one end connected to the outer end of the other arm of said bell crank lever and its other' end secured to a fixed pivot, said tension spring being adapted to lie on one side of the center line between the fixed support for said tension spring and the fixed pivot of said bell crank arm when in bolt retracted position and to lie on the other side of said center line when in pre-loaded or bolt operating position, said tension spring being stronger than said compression spring, and means atthe end of said other track for releasing said bolt retaining latch means when said tracks are substantially in alignment.

12. In track interlocking and safety stop mechanism, a movable track, a stationary track, the ends of said tracks being adapted'to be disposed in closely spaced aligned relation, an interconnected bolt and plunger carried by said movable track, a corresponding but oppositely arranged interconnected bolt and plunger carried by said stationary track, the bolt on one track being opposite the plunger onthe other track when said track ends are in alignment, track safety stop means adjacent each track end, operating connections between each of said stop means and. its respective bolt and plunger interconnecting means whereby movement of one of said bolts toward the opposite track end into interlocking position will engage the opposite plunger and cause movement of the other bolt to interlocking position and will positively move said track stops into non-blocking position, and

whereby retracting movement of said bolts to release the interconnection between said tracks is prevented whenever obstruction to movement of said track stops into track blocking position occurs.

13. In track interlocking and safety stop apparatus, a movable track, a stationary track, the ends of said tracks being adapted to be moved into closely spaced aligned relation, an interlocking bolt mounted adjacent the end of one of said tracks, a sleevemounted adjacent the end of the other of said 'tracks and adapted to receive said bolt when said tracks are aligned, a plunger in said sleeve, a pawl member pivotally mounted at the outer end of said sleeve, said bolt having an aperture for receiving said pawl whereby said bolt and plunger may be interconnected, cam means supported on said other of said tracks for maintaining said pawl in said bolt aperture during a portion of the movement of said bolt and permitting release of Said` pawl from said bolt at a predetermined point in` the withdrawing movement of said bolt, track safety stops associated with each of said tracks, and operating connections between said stops and said plunger and bolt respectively, said predetermined point in the bolt withdrawing movement at which said pawl releases said `bolt being reached only when said track stops are in track blocking position.

14. In track interlocking vand safety stop mechanisms, a pair of tracks adapted to be moved into and out of end to end alignment, a bolt carried by one track, a bolt receiving sleeve carried by the other track, a plunger movable in said Sleeve, and meansfor connecting said bolt and plungerwhen said bolt is in said sleeve and permitting release of said bolt from said sleeve at a predetermined point in the withdrawing travel `of said bolt.

15. In track interlocking and safety stop Ilmechanism, a pair of tracks adapted to be moved 4into and out of end to end alignment, a bolt carried by one track, a bolt receiving sleeve carried by the other track, a plunger movable in said sleeve, means for connecting said bolt and plunger when said bolt is in said sleeve and permitting release of said bolt from said plunger at a predetermined point in the withdrawing travel of said bolt, and track stops operable by said bolt and plunger respectively.

16. In track interlocking and safety stop mechanism, a pair of tracks adapted to be moved into and out of end `to end alignment, a bolt carried by one track, a bolt receiving sleeve carried by the other track, a plunger movable in said sleeve,

17. In track interlocking and safety stop mechanism, a pair of tracks adapted to be moved relatively into and out of end to end alignment, a movable interlock bolt mounted adjacent the end of one of said tracks, a plunger Imember mounted adjacent the end of the other of said tracks and disposed opposite said bolt and in the line of movement thereof when said track ends are aligned, safety stops carried by said tracks and adapted to be moved into and out of track blocking position, operating connections between said bolt and one of lsaid stops, operating connections between said -plunger and the other of said stops,

means Afor preventing substantial separation ofsaid bolt and plunger during movement thereof toward the track on which said bolt is carried until said safety stops are moved into track blocking position, spring means for moving said bolt, latch means for holding said bolt in retracted position, and 4means for pre-setting said spring whereby said bolt will automatically move into locking position when said latch is released.

18. In track interlocking and safety stop mechanism, a pair of tracks adapted to be moved relatively into and out of end to end alignment, a movable interlock bolt mounted adjacent the end of one of said tracks, a plunger member mounted adjacent the end of the other of said tracks and disposed opposite said bolt and in the line of movement thereof when said track ends are aligned, safety stops carried by said tracks and adapted to be moved into and out of track blocking position, operating connections between said bolt and one of said stops, operating connections between said plunger and the other of said stops, means for preventing substantial separation of said bolt and plunger during movement thereof toward the track on which said bolt is carried until said safety stops are moved into track blocking position, spring means for moving said bolt, latch means for holding said bolt in retracted position, means for pre-setting said spring whereby said bolt will automatically move into locking position when said latch is released, and means associated with said other of said tracks for releasing said latch when said tracks are substantially in alignment.

19. Track blocking and interlocking mechanism including tracks adapted to be moved relatively into and out of end to end alignment, housing members supported one on each of s aid tracks, one of said tracks being fixed and the other movable, a track interlocking bolt slidably supported in the movable track housing, a plunger disposed adjacent to said bolt and also slidably supported in said movable track housing, means for interconnecting said bolt and plunger whereby movement of said bolt in one direction will be accompanied by movement of the plunger in the opposite direction, a track safety stop operable by said bolt and plunger interconnecting means, said safety stop being disposed in tra-ck blocking position when said bolt is withdrawn or retracted into said housing and moving into non-blocking position when said bolt is advanced into interlocking position, a second plunger slidably carried by said housing on said stationary track and adapted to be disposed opposite said bolt when said tracks are substantially in alignment, a second bolt disposed in said stationary track'housing adjacent said second plunger, said second bolt being disposed in alignment with said rst namedplunger when said tracks are in alignment, means for interconnecting said second plunger and said second bolt whereby movement of said second :plunger away from the stationary track end will advance said second bolt into interlocking position, a second safety stop operatively connected to said interlocking means for said second bolt and plunger, said second safety stop being disposed in track blocking position when said second bolt is retracted and moving into non-blocking position when said second bolt is advanced, means for advancing and retracting one of said bolts to and from track interlocking position, latch means carried by said movable track housing for retaining said movable track bolt in withdrawn position, said bolt advancing and retracting means including a. spring, and ymeans for pre-settingr said spring to exert a bolt advancing force thereagainst when said ,latchv holds said bolt in withdrawn position.

20. Apparatus according to claim 7 characterized by having independent relatively light spring means tending to [urge said plungers and bolts into non-interlocking position whereby movement of said bolts into interlocking position when said tracks are Vout of alignment is resisted. 

